Demulsifiers, or emulsion breakers, are chemicals which are used to separate salted water from crude oil emulsions. They are used in the processing of crude oil which is typically recovered along with significant quantities of brine, usually in the form of sea/ocean water. It is important to remove the brine from the crude oil as quickly as possible to allow dry oil to be stored and shipped as necessary, and to allow ‘clean’ brine, i.e. brine containing no oil, to be discharged.
Common demulsifiers are generally polymeric surfactants such as copolymers of polyoxyethylene and polypropylene or alkylphenol-formaldehyde resins and/or blends of various surface active substances.
Demulsifiers, like those of the type described above, are contained within the ‘clean’ brine after demulsification. The easiest and most cost effective way of discharging the ‘clean’ brine from the crude oil stream is by pumping it back into the sea/ocean onsite. Therefore, the demulsifiers present in the ‘clean’ brine are also discharged back into the sea/ocean with the brine.
Demulsifiers of the types described above comprise phenol groups, and as such are not environmentally friendly. The discharging of these demulsifiers into the sea increases the levels of phenol groups present in the sea and thus harms marine life present in the area.
In the oilfield industry, there is a move towards more environmentally acceptable chemicals that are less hazardous than the standard production chemicals described above. For example, drilling sites in the North Sea are regulated by the rules of the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR). These rules restrict the toxicity of allowed demulsifiers and place stringent values on the biodegradability and the like of all chemicals to be used in the marine environment. However, it has been generally found that the more environmentally acceptable demulsifiers do not have the same level of efficacy as the standard production chemicals.
There is, therefore, a need for a demulsifier which shows the same or superior properties and efficacy as the standard production chemicals, but which is environmentally friendly and reaches or surpasses the rules of the OSPAR.
It is an object of the present invention to address at least one of the above or other disadvantages associated with the prior art.